Abstract: [Objective]This study aimed to ascertain the correlation between forest spatial structure and population density of Cephalcia kunyushanica (Hymenoptera:Pamphiliidae) (abbreviated as "Ck" below) in a natural secondary Japanese Red Pine (Pinus densiflora) forest in Kunyu Mountain, and to explore ecological techniques by regulating forest spatial structure for controlling Ck, provide academic direction for ecological control of the forest pest.[Method]In this study, a six-hectares sample plot was set in Kunyu Mountain natural secondary German oak Red pine mixed forest, in which mingling degree index, neighborhood comparison index and uniform angle index were selected to analyze their relations with the population density of Ck.[Result]Results showed that there was a positive correlation between the population density of Ck and the uniform angle index of P. densiflora forest in Kunyu Mountain (R²=0.821; P=0.034), and the population density was negatively correlated with both the neighborhood comparison index of diameter at breast height (R²=0.903; P=0.013) and of tree height (R²=0.906; P=0.013), but no significant correlation was found between the population density with the mingling degree index (R²=0.177; P=0.481). On P. thunbergii forest, the population density of Ck was positively correlated with the uniform angle index significantly (R²=0.858; P=0.024), but there was no significant correlation between the population density of Ck with neighborhood comparison index of diameter at breast height (R²=0.043; P=0.739), neighborhood comparison index of tree height (R²=0.237; P=0.406), and mingling uniform index (R²=0.251; P=0.390). On P. resinosa the linear relationships between the population density of Ck with all the forest spatial structure indexes were not significant, including uniform angle index (R²=0.032; P=0.772), neighborhood comparison index of diameter at breast height (R²=0.180; P=0.447) and of tree height (R²=0.194; P=0.458), and mingling index (R²=0.653; P=0.098). Among the three species, the correlation between the population density of Ck with forest spatial structure indexes of P. densiflora or P. thunbergii was stronger than that with P. resinosa. In terms of spatial structure, the uniform angle index and neighborhood comparison index were better than mingling degree index.[Conclusion]The ecological regulation function of uniform angle index and neighborhood comparison index were better than that of mingling degree index for Ck population density. The relationship between forest spatial structures and population density of Ck can be utilized for forest management. The occurrence of the pest can be reduced by afforesting uniform forest of pine tree species to improve its resistant ability to Ck, and by reducing index of neighborhood comparison, that is, by improving forest growth condition.

Key words: Cephalcia kunyushanica, population density, uniform angle, neighborhood comparison, mingling degree